1. Field of Invention
This invention relates to a scaffolding plank. More specifically, it is directed to an improved, low cost wide composite scaffolding plank formed by pinning and anchoring narrow wooden boards in side by side abutment and a method for accomplishing same. The strength of a wooden plank may be improved by cutting the plank longitudinally, alternating the wood grains of the plank sections and pinning the plank sections together as described above.
2. Related Art
Prior to this invention, two types of scaffolding planks existed in the prior art: the solid single board plank and the laminated plank. The solid single board plank comprises one wide wooden board. The laminated plank is constructed from multiple layers of wooden strips glued together. Each of the two types of prior art scaffolding planks has disadvantages.
Due to the limited resources of old growth forests and the harvesting schemes for new growth timber, the yield of wooden boards wide enough from which to construct a solid single board plank is decreasing. Typically, only the center portion of a large tree is sufficiently broad to produce a solid single board plank. Thus, with decreasing yield, the solid single board planks are becoming more costly and difficult to make. The main disadvantage of laminated planks is that laminated planks primarily consist of glued layers of wooden strips, which glued layers of wooden strips absorb substantial amounts of moisture. After absorbing enough moisture, the wooden fibers of the laminated plank soften and the moisture hastens the decay of the laminated plank. Likewise, any time one of the veneers of the laminated plank cracks, the laminated plank looses its strength and consistency and can also no longer be used as a scaffolding. Thus, there has existed a need for a scaffolding plank that is as strong and as durable as a solid single board plank, that does not require the use of wider trees, and that does not have the weaknesses inherent in laminated planks. It would thus be beneficial to the prior art to construct a scaffolding plank that is as strong and as durable as a solid single board plank, that does not require the use of wider trees, and that does not have the weaknesses inherent in laminated planks.
Scaffolding planks are however strictly regulated. The Occupational Safety and Health Administration, OSHA, as well as the Southern Pine Inspection Bureau, SPIB, outline strict standards for scaffolding planks. Pursuant to such regulations, scaffolding planks must comply with certain width, breakage, and quality standards. The OSHA and SPIB standards are strict because workers entrust their lives to the scaffolding. The prior art would thus benefit from a scaffolding plank, as described above, that meets and preferably exceeds the OSHA and SPIB standards. The OSHA standard found at 19 C.F.R. § 1926, Subpart L, including Appendix A, recommends scaffolding for typical medium loads to be 2″×10″ (nominal). (Dimensions described in this specification are nominal dimensions, unless otherwise stated. Nominal dimension units are typically ½″ greater than actual size dimensions.)
Because the lives of workers hinge on the integrity of scaffolding planks, any safety factors that can be added to a scaffolding plank greatly enhance the value of the scaffolding plank. It would be beneficial to the prior art to provide a scaffolding plank, as described above, which also includes an additional worker safety factor.
Manufactured wide boards for scaffolding are unknown to the prior art. Prior references, however, disclose structural wood assemblies formed from a plurality of smaller wood boards. Illustrative of such wood assemblies are U.S. Pat. No. 2,650,395 that issued to de Anguera on Sep. 1, 1953, U.S. Pat. No. 5,120,378 that issued to Porter et al. on Jun. 9, 1992, U.S. Pat. No. 4,534,448 that issued to Trainer on Aug. 13, 1985, U.S. Pat. No. 1,167,988 that issued to Faulkner on Jan. 11, 1916, and U.S. Pat. No. 2,569,450 that issued to Bouton on Oct. 2, 1951. None of these devices provides a truly simple remedy for the problem of providing manufactured wide boards that can meet the OSHA standards for scaffolding.
The assembly shown in U.S. Pat. No. 2,650,395 discloses a method of forming wood flooring from relatively narrow pieces of wood having varying lengths. The pieces of wood are placed in a number of parallel rows wherein the pieces are placed end to end. A plurality of spaced thin connector keys is driven into lateral bores in the aligned pieces and holds the pieces together.
U.S. Pat. No. 5,120,378 discloses an apparatus and method for producing a prestressed wood material beam. The wood beams are held together using adhesives or mechanical fasteners such as nails or staples.
The other cited references, including those below, disclose wood panels, such as used for bowling alley lanes or structural walls, or walking surfaces comprising loosely associated narrow planks. None of the completed structures teach the wooden components being held together in compression.
U.S. Pat. No. 3,144,892, issued Aug. 18, 1964 to Webster, discloses and claims a method of fabricating panels that are formed by attaching a plurality of boards with relatively soft metal dowels. The dowels are driven into aligning bores that have been drilled through the narrow boards. Webster differs or teaches away from the present invention by having at least three significant limitations. First, Webster orients the plurality of boards such that their wider sides are contiguous. The present invention orients the boards so that their narrower sides are contiguous. This orientation is difficult to achieve without splitting the boards, but is achieved by the disclosed method. Second, Webster uses boards that have a tongue-and-groove channeling between boards to align them. The present method uses flat boards that are aligned with flat sides adjacent and tightly positioned together by the disclosed board pinning machine. Webster further requires tongue-and-groove channeling for releasing cuttings from bores during the drilling operation. Third, Webster uses the groove channels in the boards to “function as lead holes for starting the drill tips into each succeeding panel component” when drilling bores for the securing metal dowels. The present invention, due in part to its board pinning machine securely holding the boards, bores holes directly through the smaller boards without the need for pilot or lead holes.
Danish Patent 84807, published May 5, 1958 and issued to Larsen discloses a system of attaching scaffolding boards at their contiguous ends. Larsen does not teach pinning of the boards together to form a single plank. Rather, Larsen teaches a system of U-shaped clamps that hook into the ends of each scaffold board for wood framed scaffolding, thus aligning the boards into a smooth walk surface. Larsen teaches this by aligning each pair of boards' ends over a wooden support beam, and hooking the U-shaped clamps through holes in the boards and around the support beam. Transverse connecting irons are used solely for the purpose of providing a resting support for the U-shaped clamps, and do not teach pinning the boards together. This system provides a loose connection of several boards, without forming a single plank as described in the present invention. Further, Larsen is limited to specific sized support cross-beams (typically 4″×4″ nominal) to mate properly with the U-shaped clamps.
Though the above mentioned devices and assemblies may be helpful for their intended purposes, none disclose a manufactured scaffolding plank that meets OSHA and SPIB requirements, that is as strong and as durable as a solid single board plank, that does not require the use of wider trees, and that does not have the weaknesses inherent in laminated planks.